Wireless communication apparatus, wireless communication system, and wireless communication method

ABSTRACT

A wireless communication apparatus, a wireless communication system, and a wireless communication method enabling any plurality of apparatuses to engage in time division multiplex communication for communicating a plurality of data even if not all apparatuses in the network are accurately synchronized, perform a time division multiplex connection method of an autonomous distributed network that performs a continuous receiving (scan) operation over a frame period so as to obtain a grasp of the wireless communication apparatuses located at the neighborhood at predetermined periods, that includes the steps of receiving beacon signals from other wireless communication apparatuses to obtain a grasp of the wireless communication apparatuses that they are communicable with, calculating the reception slot of the wireless communication apparatus from the received beacon information, setting its own reception slot so as not to collide with the set situation thereof, and forming network autonomously engaging in time division multiplex communication with other wireless communication apparatuses located at the neighborhood.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.10/506,461, filed Jul. 11, 2005, which is a 371(c) National Stage Entryof PCT/JP04/00021, filed Jan. 7, 2004, which claims benefit to JapanPatent No. 2003-001177, filed Jan. 7, 2003, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a wireless communication apparatus, awireless communication system, and a wireless communication methodemploying a time division multiplex connection method based onasynchronous control of communication apparatuses in an autonomousdistributed network.

BACKGROUND ART

At present, the method of administration by direct communication byterminal stations without arranging a base station in a network like anad hoc mode of a wireless local area network (wireless LAN) based on theIEEE802.11 standard is known.

Further in recent years, as a technology enabling data communication ata close distance at an ultra-high speed, unlike a communication systemwhich has conventionally used a certain specific carrier, ultra-wideband wireless communication for transmitting information carried on avery short pulse sequence is attracting attention.

This ultra-wide band wireless communication can directly and wirelesslytransmit a baseband signal, so enables a simple circuit configurationand is mentioned as a strong candidate for a personal area networkassuming a data transmission rate of about 100 Mbps.

Further, as a conventional time division multiplex connection method, asused in mobile phone and other systems, the method of arranging a basestation in the network and making all moving terminal stations performtime divisional multiplex connections in synchronization with signalsfrom the base station is generally known.

In order for a plurality of apparatuses to simultaneously engage inultra-wide band communications, the method of time division multiplexconnection has generally been considered.

Further, in order to form a wireless network among a plurality ofapparatuses, the method of arranging a control station referred to as a“coordinator” at the center of the network and utilizing centralmanagement by the control station for time division multiplexing of timefor which a plurality of apparatuses engage in ultra-wide bandcommunication is generally known (IEEE802.15.3).

In the recently hot ultra-wide band communication, however, an extremelyweak pulse sequence was used for communication, so there was thedisadvantage that easy configuration of the means for detecting thecarrier which had been utilized in the conventional wireless system washard.

Further, in the conventional ad hoc mode of a wireless LAN, it was notnecessary to establish synchronization among all terminals, but therewas the disadvantage that a means for detecting the carrier wasnecessary before transmitting information so as to prevent collisionwith communication of other terminals. Accordingly, the technologycannot be utilized for wireless communication.

Further, when using a plurality of terminals operating in the ad hocmode of a wireless LAN to form a network, since it was not known wheninformation would arrive from another terminal, it was necessary toconstantly operate to be ready to receive signals, therefore there wasthe disadvantage that reduction of the power consumption was difficult.

Further, when operating in the ad hoc mode, since other apparatuses werenot constantly synchronized with, there was the disadvantage that timedivision multiplex communication was hard when a plurality ofcommunication links repeatedly transferred information in apredetermined period.

In conventional mobile phone and other time division multiplexcommunication systems, in order to avoid collision of slots divided intime, all terminals in the system had to be synchronized with the basestation, so it was necessary to mount sophisticated mechanisms enablingall terminal stations to synchronize with the base station.

Further, when communicating by time division multiplexing in aconventional wireless network, it was necessary to arrange a controlstation referred to as a “coordinator” at the center of the network andhave the control station centrally manage operations.

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a wirelesscommunication apparatus, a wireless communication system, and a wirelesscommunication method enabling any plurality of apparatuses to engage intime division multiplex communication for a plurality of datacommunications even without all apparatuses inside the networkcorrecting synchronizing.

A second object of the present invention is to provide a wirelesscommunication apparatus, a wireless communication system, and a wirelesscommunication method enabling easy time division multiplex communicationwhen any communication apparatuses form a network ad hoc.

A third object of the present invention is to provide a wirelesscommunication apparatus, a wireless communication system, and a wirelesscommunication method enabling access control without arranging aspecific control device in ultra-wide band wireless communication.

A fourth object of the present invention is to provide a wirelesscommunication apparatus, a wireless communication system, and a wirelesscommunication method enabling a receiving operation only when requiredwithout always engaging in a receiving operation and accordinglyenabling easy reduction of the power consumption.

To attain the above objects, a first aspect of the present invention isa wireless communication apparatus communicating with another wirelesscommunication apparatus in an autonomous distributed network without anyspecific control station apparatus, the wireless communication apparatuscomprising a frame period setting means for setting a predeterminedframe period by each wireless communication apparatus; a data slotsetting means for setting slots serving as data transmission units; anda reception slot setting means for setting at least one reception slotfor receiving a signal in the frame period.

Preferably, it further comprises a transmitting means for transmitting abeacon signal to another wireless communication apparatus at apredetermined timing of the frame period, which beacon has informationabout a timing of the reception slot set by the reception slot settingmeans and a receiving means for receiving a signal which is transmittedby another wireless communication apparatus.

Preferably, the receiving means receives signal at a timing of thereception slot set by the reception slot setting means.

A second aspect of the present invention is a wireless communicationapparatus for communicating with another wireless communicationapparatus in an autonomous distributed network without any specificcontrol station apparatus, the wireless communication apparatuscomprising a frame period setting means for setting a predeterminedframe period; a data slot setting means for setting slots serving asdata transmission units; a scan period setting means for setting anyscan period longer than the frame period; and a scanning means forreceiving a beacon signal transmitted from another wirelesscommunication apparatus over a time of the frame period unit.

Preferably, it further comprises a managing means for converting thetiming of the received beacon signal and the timing of the receptionslot into its own slot positions and a transmitting means fortransmitting a signal at the timing of the reception slot of thecorresponding wireless communication apparatus when there is datadirected to another wireless communication apparatus.

Preferably, it further comprises a control means for making thetransmitting means transmits a signal at the timing of the receptionslot of the corresponding wireless communication apparatus when there isdata directed to the other wireless communication apparatus, thescanning means obtaining the timing of the beacon signal and the timingof the reception slot from the other wireless communication apparatus.

A third aspect of the present invention is a wireless communicationsystem for communication among a plurality of wireless communicationapparatuses in an autonomous distributed network without a specificcontrol station apparatus, wherein each of the wireless communicationapparatuses configuring the network comprises a frame period settingmeans for setting a predetermined frame period; a data slot settingmeans for setting slots serving as data transmission units; a beaconslot setting means for setting beacon slots for transmitting beaconsignals at a predetermined timing of the frame period; and a receptionslot setting means for setting at least one reception slot for thereceiving operation in the frame period.

Preferably, it transmits the beacon signal at the timing of the head ofthe frame period.

Preferably, timings by which wireless communication apparatuses transmitbeacons are arranged so as not to overlap each other.

A fourth aspect of the present invention is a wireless communicationmethod for communication among a plurality of wireless communicationapparatuses in an autonomous distributed network without a specificcontrol station apparatus, wherein each wireless communication apparatussets a predetermined frame period and slots serving as data transmissionunits and sets at least one beacon slot for transmitting the beaconsignal at a predetermined timing of the frame period and reception slotfor the receiving operation in the frame period.

Preferably, it transmits a beacon signal which has information about thetiming of the set reception slot and informs the presence to anotherwireless communication apparatus located in the neighborhood.

A fifth aspect of the present invention is a wireless communicationmethod for communication among a plurality of wireless communicationapparatuses in an autonomous distributed network without a specificcontrol station apparatus, wherein each wireless communication apparatussets a predetermined frame period and slots serving as data transmissionunits, provides any scan period longer than the frame period, performsscan processing for continuous reception over the time of the frameperiod unit, and receives a beacon signal transmitted from anotherwireless communication apparatus located in the neighborhood.

Preferably, it manages the timing of the reception of the beacon signaltransmitted from the other wireless communication apparatus and thetiming of the reception slot.

A sixth aspect of the present invention is a wireless communicationmethod for communication among a plurality of wireless communicationapparatuses in an autonomous distributed network without a specificcontrol station apparatus, comprising, at each wireless communicationapparatus, the steps of: setting a predetermined frame period and slotsserving as data transmission units, setting at least one beacon slot fortransmitting a beacon signal at a timing of the head of the frame periodand a reception slot for a receiving operation in the frame period,transmitting a beacon signal which has information about the timing ofthe set reception slot and notifies existence to another communicationapparatus located in the neighborhood, setting any scan period longerthan the frame period, and performing scan processing for continuousreception over the time of the frame period unit.

Preferably, it receives the beacon signal of another wirelesscommunication apparatus located in the neighborhood, manages the timingof the reception of the beacon signal and the timing of the receptionslot, and transmits a signal at the timing of the reception slot of thecorresponding wireless communication apparatus when communicatingdirected to another wireless communication apparatus.

According to the present invention, by providing a frame period commonto all apparatuses, dividing the frame to slots of further shorter timeunits, setting at least one beacon slot to be periodically transmittedat a timing of the head of the frame period set by itself and areception slot received by itself, writing the position of the receptionslot in the beacon information and transmitting the beacon, and therebynotifying another apparatus located at the neighborhood.

Further, each apparatus provides any scan period with a period longerthan the frame period. When that period passes, it engages in areceiving operation over the frame period, receives the beacon from anapparatus located at the neighborhood, and confirms the apparatuslocated at the neighborhood.

Then, each apparatus repeatedly and periodically engages in receptionprocessing when the timing of the reception slot arrives.

At least one reception slot may be provided in the frame period, but aplurality of reception slots can be provided according to the need ofthe apparatuses as well.

When transmitting data to a certain apparatus, the invention transmitsdata at the timing of the position of the reception slot written in thebeacon signal from a surrounding apparatus from which a signal can bereceived by the scanning.

The apparatus receiving the data can employ a configuration also capableof handling large capacity data communication by addition of a receptionslot whenever addition becomes necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of an example of the arrangement of communicationapparatuses configuring a wireless communication system according to thepresent invention.

FIG. 2 is a view of the configuration of a frame period and theconfiguration of a scan period employed in a wireless communicationapparatus according to the present embodiment.

FIGS. 3A to 3E are charts concretely showing a series of operations ofthe wireless communication system of FIG. 1 in a time series.

FIG. 4 is a view of the configuration of an embodiment of a wirelesscommunication apparatus according to the present invention.

FIG. 5 is a view of an example of the configuration of beaconinformation according to the present embodiment.

FIG. 6 is a view of an example of the configuration of data informationaccording to the present embodiment.

FIG. 7 is a flow chart for explaining a series of operations of awireless communication apparatus according to the present embodiment.

BEST MODE FOR WORKING THE INVENTION

Below, embodiments of the present invention will be explained withreference to the attached drawings.

FIG. 1 is a view of an example of the arrangement of communicationapparatuses configuring a wireless communication system according to thepresent invention.

A wireless communication system 10 of the example of FIG. 1 shows a casewhere there are eight wireless communication apparatuses 11 to 18.

Namely, FIG. 1 shows the situation where the wireless communicationapparatus 11 to the wireless communication apparatus 18 are distributedin the same space.

Further, in FIG. 1, the communication ranges of the wirelesscommunication apparatuses 11 to 18 are indicated by broken lines. Theseare defined as ranges where not only is communication with otherwireless communication apparatuses within those ranges possible, butalso where signals transmitted by oneself cause interference.

In the wireless communication system 10 of FIG. 1, the wirelesscommunication apparatus 11 is in a range capable of communicating withthe neighboring wireless communication apparatuses 12, 13, and 17.

The wireless communication apparatus 12 is in a range capable ofcommunicating with the neighboring wireless communication apparatuses 11and 13.

The wireless communication apparatus 13 is in a range capable ofcommunicating with the neighboring wireless communication apparatuses11, 12, and 15.

The wireless communication apparatus 14 is in a range capable ofcommunicating with the neighboring wireless communication apparatus 15.

The wireless communication apparatus 15 is in a range capable ofcommunicating with the neighboring wireless communication apparatuses13, 14, and 16.

The wireless communication apparatus 16 is in a range capable ofcommunicating with the neighboring wireless communication apparatuses 15and 18.

The wireless communication apparatus 17 is in a range capable ofcommunicating with the neighboring wireless communication apparatus 11.

The wireless communication apparatus 18 is in a range capable ofcommunicating with the neighboring wireless communication apparatus 16.

The wireless communication system 10 according to the present embodimentemploys an access control method where the wireless communicationapparatuses 11 to 18 utilize one wireless transmission channel in a timedivision manner while considering interference with other wirelesscommunication apparatuses around them.

FIG. 2 is a view of the configuration of a frame period and theconfiguration of a scan period employed in a wireless communicationsystem according to the present embodiment.

In the present embodiment, as shown in FIG. 2, a beacon slot (S0: BSLT)for transmitting the beacon at a predetermined timing and data slots (S1to S255: DSLT) for receiving the data are arranged. A total of 256 slotstogether form a frame period FLMP. A frame period FLMP is set at forexample 30 ms to 40 ms.

This frame period FLMP is provided with a scan frame SCNF and a normalframe NRMF. Each wireless communication apparatus is configured toperform a scan operation for obtaining a grasp of the existence of asurrounding wireless communication apparatus in a scan frame SCNF.

32 frames of this scan frame SCNF (F0) and normal frames NRMF (F1 toF31) together form the scan period SCNP.

Note that the parameters of the number of slots and the number of framesindicated here are numerical values set for convenience and are notlimited to the numerical values indicated here.

FIGS. 3A to 3E are views concretely showing a series of operations ofthe wireless communication system 10 of FIG. 1 by time series.

These show operations in the wireless communication apparatus 13 at theposition of FIG. 1 in comparison with the communication apparatuses 11,12, and 15 located at its periphery.

FIG. 3A shows the communication state of the wireless communicationapparatus 11; FIG. 3B shows the communication state of the wirelesscommunication apparatus 12; FIG. 3C shows the communication state of thewireless communication apparatus 15; and FIG. 3D and FIG. 3E show theconcrete operation state of the wireless communication apparatus 13.

Note that, in FIG. 3A to FIG. 3E, BCN indicates a beacon, RSLT indicatesa reception slot, CNTRCV indicates continuous reception, SCNO indicatesa scan operation, and DRCV indicates data reception. Further, FIMPindicates a frame period and designates a period from a beacontransmitted by a wireless communication apparatus up to the beacontransmitted by the next wireless communication apparatus (super frame).SCNF indicates a scan frame, SCNP indicates a scan period, and tindicates the time.

Further, as shown in FIG. 3A to FIG. 3D, the beacon transmissionpositions of the wireless communication apparatuses 11, 12, 13, and 15are arranged so as not to overlap each other. This is done in order toavoid collision among beacons. Accordingly, the head positions of theframe periods set by the wireless communication apparatuses are arrangedshifted from each other.

As shown in FIG. 3D and FIG. 3E, the wireless communication apparatus 13transmits the beacon BCN in the frame period FLMP set in advance,engages in a continuous receiving operation (CNTRCV) in the scan periodSCNF set in advance, and engages in a scan operation (SCNO).

At this time, it receives the beacon signal of the wirelesscommunication apparatus 12, the beacon signal of the wirelesscommunication apparatus 11, and the beacon signal of the wirelesscommunication apparatus 15 located at its periphery as shown in FIG. 3Ato FIG. 3C.

It can obtain a grasp of the reception slot RSLT set by each wirelesscommunication apparatus by these beacon signals.

The wireless communication apparatus 13, as shown in FIG. 3A to FIG. 3D,arranges its own reception slot RSLT 13 at a position not colliding withthe reception slots RSLTs of these wireless communication apparatuses11, 12, and 15 at its periphery and transmits the setting by the nextbeacon information BCN13 transmitted by itself to the surroundingwireless communication apparatuses 11, 12, and 15.

By performing a series of operations for each scan period FLMP, it ispossible to arrange the slot for transferring data while obtaining agrasp of the existence of surrounding wireless communicationapparatuses.

Here, this wireless communication apparatus 13 can receive data from theother wireless communication apparatuses 11, 12, and 15 located at theneighborhood by receiving data at the timing of the reception slot setby itself.

Further, when it is necessary to transmit data toward the othercommunication apparatuses 11, 12, and 15, this wireless communicationapparatus 13 can engage in a transmitting operation of data matching thetiming of the reception slot of the destination wireless communicationapparatus so as to transmit data without collision with communicationfrom other wireless communication apparatuses.

Note that, in the above example, the example of writing in a beaconsignal the reception slot RSLT set by the wireless communicationapparatus and informing the other wireless communication apparatuses ofone's own reception slot was explained, but it is also possible todetermine a predetermined slot of the frame as the reception slot inadvance. For example, when wireless communication terminals belonging tothe network transmit beacons at timings shifted from each other, and apredetermined period immediately after the transmission of a beacon isdetermined as the reception slot of the beacon transmitting terminal,there is no longer a need for writing the timing of the reception slotin the beacon and informing this as in the above example.

In this case, if controlling the arrangement of beacons transmitted bythe wireless communication apparatuses so as not to overlap each other,the reception slot started along with this can avoid collision.

An example of controlling the arrangement of beacons transmitted by thewireless communication apparatuses so as not to overlap each other willbe explained. The positions of the beacons from the other wirelesscommunication apparatuses which an apparatus can receive by a scanoperation are grasped at a relative time from one's own beacontransmitting time and stored in a storage means. Then, the stored beacontransmitting positions from the other wireless communication apparatusesare written in one's own beacon and informed to the surrounding wirelesscommunication apparatuses. The surrounding wireless communicationapparatuses obtaining that information avoid timings which have beenalready used as the beacon transmitting timings by wirelesscommunication apparatuses other than itself in the frame period andstart the frame period. As a result, beacons can be arranged so that thebeacon transmission positions of the wireless communication terminals donot overlap each other as shown in FIG. 3A to FIG. 3D.

Below, an explanation will be given of a concrete example of theconfiguration of a wireless communication apparatus according to thepresent embodiment.

FIG. 4 is a view of the configuration of an embodiment of a wirelesscommunication apparatus according to the present invention.

The wireless communication apparatuses 11 to 18 of FIG. 1 have the sameconfiguration, so the wireless communication apparatuses are representedby the notation 100 here.

This wireless communication apparatus 100, as shown in FIG. 4, has atime counting portion 101, a frame managing portion 102, an informationstorage portion 103, an interface 104, a transmission buffer 105, a slotmanaging portion 106, a reception buffer 107, a beacon generatingportion 108, a beacon analyzing portion 109, a wireless transmittingportion 110, a timing control portion 111, a wireless receiving portion112, and an antenna 113.

Note that for example the frame managing portion 102 configures theframe period setting means and the scan period setting means, and theslot managing portion 106 and the beacon generating portion 108 etc.configure the reception slot setting means.

The time counting portion 101 includes for example a counter, countstimes of the frame period FLIMP common to all apparatuses and the scanperiod SCNP, etc. and outputs the counting result to the frame managingportion 102.

The frame managing portion 102 sets the frame period FIMP set by thiswireless communication apparatus 100 and its start time and the scanperiod SCNP.

The information storage portion 103 stores the information of the beacontransmission position and the reception slot position of the wirelesscommunication apparatus located at the neighborhood under the managementof the slot managing portion 106.

The interface 104 becomes the input/output terminal between a notillustrated application device connected to this wireless communicationapparatus 100 and the transmission buffer 105 and reception buffer 107.

The transmission buffer 105 stores the information to be transmittedfrom the application device connected via the interface 104.

When receiving a data transmission request via the interface 104 whentransmitting data, the transmission buffer 105 notifies the informationincluding the destination information of the data to the slot managingportion 106.

The slot managing portion 106 designates the reception slot of thiswireless communication apparatus 100 and the slot for transmissiondirected to the other wireless communication apparatuses.

The slot managing portion 106 fits the timing information fromindividual wireless communication apparatuses to the slots of its ownframe period FLMP and stores the same as the timing information of thewireless communication apparatuses located at its own neighborhood inthe information storage portion 103.

The reception buffer 107 stores the information wirelessly received fordelivering the information to the application device connected.

The beacon generating portion 108 generates the identifier of thiswireless communication apparatus 100 and the set reception slot as abeacon signal based on an instruction of the slot managing portion 106.

The beacon analyzing portion 109 analyzes the timings of the beacons andthe reception slots from the received beacon signals and outputs theanalysis results to the slot managing portion 106.

The wireless transmitting portion 110 modulates the beacon and thetransmission data to be transmitted to convert them to a wirelesstransmission signal and emits the wireless signal through the antenna113 to the transmission medium (air) at the timing designated by thetiming control portion 111.

The timing control portion 111 designates the transmission timing in thewireless transmitting portion 110 by the instruction of the slotmanaging portion 106 and designates the timing for reception in thewireless receiving portion 112.

The wireless receiving portion 112 receives the signal sent from theother wireless communication apparatus via the antenna 113 at thepredetermined timing designated by the timing control portion 111.

The antenna 113 emits the wireless signal from the wireless transmittingportion 110 into the transmission medium (air), receives the wirelesssignal from the transmission medium (air), and supplies the same to thewireless receiving portion 112.

The wireless communication apparatus 100 having the above configurationreceives a notification from the time counting portion 111 when the scanperiod arrives. The frame managing portion 102 notifies the reception ofa whole frame to the slot managing portion 106. The slot managingportion 106 issues an instruction to the timing control portion 111 andthereby makes the wireless receiving portion 112 operate over thepredetermined time.

The beacon signals received at the wireless receiving portion 112 areanalyzed in the beacon analyzing portion 109, then information of thetimings of the beacons and the timings of the reception slots of thewireless communication apparatuses is notified to the slot managingportion 106.

The slot managing portion 106 fits the timing information from theseindividual wireless communication apparatuses to the slots of its frameperiod FLMP and stores the same as the timing information of thewireless communication apparatuses located at the neighborhood in theinformation storage portion 103.

Further, when transmitting a beacon, the frame managing portion 102delivers an instruction for transmitting the beacon at the timing of thehead of the frame to the slot managing portion 106. The slot managingportion 106 requests the generating portion of the beacon signal to thebeacon generating 108 and notifies the timing of its own reception slotto the timing control portion 111.

The beacon generating portion 108 generates a beacon signal writing theposition of its own reception slot.

Then, the timing control portion 111 transfers an instruction forwireless transmission to the wireless transmitting portion 110 when thetiming of the head of the frame arrives, whereupon the wirelesstransmitting portion 110 transmits the beacon via the antenna 113.

When transmitting data, first the transmission buffer 105 receives adata transmission request via the interface 104 and notifies informationincluding the destination information of the data to the slot managingportion 106.

The slot managing portion 106 refers to the timing of the reception slotof the destination wireless communication apparatus from the storageinformation of the information storage portion 103. If the receptionslot is set, it sends the timing to the timing control portion 111.

When the timing of the predetermined slot arrives, the timing controlportion 111 transfers the instruction for wireless transmission to thewireless transmitting portion 110. Due to this, the wirelesstransmitting portion 110 transmits the data to be transmitted via theantenna 113.

When receiving data, first the slot managing portion 106 notifies thetiming of its own reception slot to the timing control portion 111 whichthen makes the wireless receiving portion 112 operate at the timing ofthe reception slot.

The data signal received at the wireless receiving portion 112 is storedin the reception buffer 107. The data is delivered to an applicationdevice connected to the wireless communication apparatus 100 via theinterface 104 at the predetermined timing when constant data can becorrectly collected.

FIG. 5 is a view of an example of the configuration of the beaconinformation according to the present embodiment.

This beacon information 200 may be configured by information distinctiveto a wireless communication apparatus such as a communication apparatusaddress (CMADR) 201 like a MAC address, beacon period information (BPI)202 indicating the beacon transmission period of this wirelesscommunication apparatus, reception slot information (RSN) 203representing the timing set as the reception slot, and further,according to need, the reception slot information.

Further, it is configured provided with a reservation region (RSV) 204until the predetermined information length and a CRC 205 for detectingthe error added to the tail.

Note that here, for convenience, the general value of the length of eachinformation is additionally shown.

In FIG. 5, the communication apparatus address (CMADR) 201 is indicatedas 6 bytes, the beacon period information (BPI) 202 is indicated as 1byte, and the reception slot information (RSN) 203 is indicated as 1byte.

FIG. 6 is a view of an example of the configuration of the datainformation according to the present embodiment.

This data information 300 is comprised of MAC header information (HDI)301 including for example the destination address information, a datapayload (DPLD) 302 as the content of the data to be transmitted, and aCRC 303 for detecting error added to the tail.

Note that here, for convenience, the general value of the length of eachinformation is additionally shown.

In FIG. 6, the data payload (DPLD) 302 is envisioned as having acapacity of about 1500 bytes as a size by which an IP packet can betransmitted well.

Next, the series of operations of the wireless communication apparatus100 having the above configuration will be explained with reference tothe flow chart of FIG. 7.

First, after the power is turned on, the wireless communicationapparatus 100 sets its own frame period FLMP and beacon transmissionposition and also sets the scan period SCNP.

Then, it sets the scan time over the frame period FLMP (ST3) and entersinto the beacon receiving operation (ST4).

Here, if receiving beacons, the received positions (timings) arecalculated and recorded from the beacon reception positions (timings)and the reception slot information written in those beacons (ST5).

On the other hand, when it is decided at step ST4 that no beacons werereceived, the routine shifts to the processing of step ST6.

At step ST6, it is decided whether or not the scan time has passed. Ifthe scan time has not passed, the routine returns to the processing ofstep ST4. If the scan time has passed, the routine shifts to theprocessing of step ST7.

Further, the apparatus sets its own reception slot so as to avoidcollision with the reception slot positions of these other wirelesscommunication apparatuses and writes this as the beacon information(ST7).

Then, the apparatus decides whether or not the timing of thetransmission position of the beacon (head of frame) has arrives (ST8)and transmits the beacon signal only when the timing arrives (ST9).

The reception processing at one's own reception slot decides whether ornot its own reception slot has arrived (ST10), activates the wirelessreceiving portion 112 when the reception slot arrives, and engages inthe reception processing (ST11).

Here, it decides whether or not data directed to itself has beenreceived (ST12). If received, it stores the data in the reception buffer107 (ST13), then the routine shifts to the processing of step ST14. Whenreceiving beacons of other wireless communication apparatuses at thistime, it may engage in the beacon reception processing.

The routine shifts to the processing of step ST14 both when thereception slot does not arrive in the decision of step ST10 and whendata directed to itself was not received in the decision of step ST12.

The transmission processing for transmitting data decides whether or nota data transmission request was received by the transmission buffer 105via the interface 104 (ST14).

It then acquires address information of the destination wirelesscommunication apparatus based on the request (ST15).

Then, it decides whether or not the reception slot information of thewireless communication apparatus corresponding to the address isregistered (ST16) and sets the transmission at that timing whenregistered.

That is, it decides whether or not the timing of the reception slot ofthe corresponding wireless communication apparatus has arrived (ST17)and performs the data transmission processing only when the timing hasarrived (ST18). Then, the routine shifts to the processing of step ST19.

Here, even when the decision of step ST14 is that there is no datatransmission request and the reception slot of the correspondingwireless communication apparatus is not registered, the routine shiftsto the processing of step ST19.

At step ST19, it decides whether or not the scan period set at step ST2has arrived. When it has not arrived, the routine shifts to theprocessing of step ST8, where it transmits the beacon at the timing forperiodically transmitting the beacon and engages in the receivingoperation for the reception slot.

Further, when the scan period arrives, the routine shifts to theprocessing of step ST3, where it performs the scan operation forobtaining a grasp of the existence of the surrounding wirelesscommunication apparatuses again.

As explained above, according to the present embodiment, the timedivision multiplex connection method of an autonomous distributednetwork comprises performing a continuous receiving (scan) operationover a frame period so that each wireless communication apparatus canobtain a grasp of the wireless communication apparatuses located at theneighborhood at predetermined periods, receiving beacon signals fromother wireless communication apparatuses to obtain a grasp of thewireless communication apparatuses communicable with, calculating thereception slot of the wireless communication apparatus from the receivedbeacon information, setting a reception slot so as not to collide withthe set situation thereof, and autonomously engaging in time divisionmultiplex communication with other wireless communication apparatuseslocated at the neighborhood, so there is the advantage that timedivision multiplex connection method by asynchronous control ofcommunication apparatuses in the autonomous distributed network can beeasily realized.

Further, by providing a frame period common to all apparatuses, dividingthe frame to slots of further shorter time units, and communicating inunits of the slots, it is possible to communicate with a high randomaccessibility on a wireless transmission channel while forming an ad hocnetwork without synchronization with the surrounding apparatuses.

Further, by providing a frame period common to the wirelesscommunication apparatuses and periodically transmitting beacons at thetiming of the head of the frame period, all wireless communicationapparatuses can obtain a grasp of the existence of the other wirelesscommunication apparatuses located at their neighborhood.

Further, by periodically transmitting beacons in the frame period set byeach apparatus and setting at least one reception slot for reception bya communication apparatus, it is possible to utilize other regions forcommunication of the other apparatuses and possible to improve therepeat utilization efficiency of a wireless transmission channel.

Further, by providing any scanning period in each apparatus andperforming continuous reception (scanning) in units of frame periods, itis possible to obtain a grasp of other apparatuses located at theneighborhood.

Further, even if deviation occurs in the operating clock with otherapparatuses, by ignoring the past scan information and making the newestscan information valid, communication is possible without regard as toclock deviation with other apparatuses.

From the above, a wireless communication system and wirelesscommunication method for communicating without among a plurality ofapparatuses requiring clock correction can be realized.

INDUSTRIAL APPLICABILITY

The present invention enables communication with a high randomaccessibility on a wireless transmission channel while forming an ad hocnetwork without synchronization with surrounding apparatuses, enablesall communication apparatuses to obtain a grasp of the existence of theother communication apparatuses located at their neighborhood, enablesimprovement of the repeat utilization efficiency of the wirelesstransmission channel, enables a grasp of other apparatuses located atthe neighborhood to be obtained, and enables communication withoutregard as to clock deviation with other apparatuses, therefore thepresent invention can be applied to a system for communication withother wireless communication apparatuses in an autonomous distributednetwork without a specific control station apparatus.

LIST OF REFERENCES

-   -   10 . . . wireless communication system    -   11 to 18, 100 . . . wireless communication apparatus    -   101 . . . time counting portion    -   102 . . . frame managing portion    -   103 . . . information storage portion    -   104 . . . interface    -   105 . . . transmission buffer    -   106 . . . slot managing portion    -   107 . . . reception buffer    -   108 . . . beacon generating portion    -   109 . . . beacon analyzing portion    -   110 . . . wireless transmitting portion    -   111 . . . timing control portion    -   112 . . . wireless receiving portion    -   113 . . . antenna, FLMP frame period    -   SCNP . . . scan period    -   BLST . . . beacon slot    -   DSLT . . . data slot    -   SCNF . . . scan frame    -   NRMF . . . normal frame    -   BCN . . . beacon    -   RSLT . . . reception slot    -   200 . . . beacon information    -   201 . . . communication apparatus address (CMADR)    -   202 . . . beacon period information (BPI)    -   203 . . . reception slot number (RSN)    -   204 . . . reservation region (RSV)    -   205 . . . CRC    -   300 . . . data information    -   301 . . . MAC header information (HDI)    -   302 . . . data payload (DPLD)    -   303 . . . CRC

The invention claimed is:
 1. A wireless communication device forcommunicating with another wireless communication device in anautonomous distributed network without a designated control station,said wireless communication device comprising: a processor and a memoryincluding instructions which, when executed by the processor, controlgenerating a frame period for setting a predetermined frame period forthe wireless communication device, wherein the frame period has aplurality of data slots serving as data transmission units; setting ascan period, the scan period being longer than said predetermined frameperiod; performing scan operation to engage in a continuous receivingoperation over a time of the predetermined frame period; setting atleast one reception slot for receiving a signal in said predeterminedframe period; generating beacon information for generating a beaconsignal that includes at least one of information indicating thereception slot or information indicating the predetermined frame period;and transmitting a beacon signal for notifying its presence to anotherwireless communication device located in the neighborhood.
 2. Thewireless communication device as set forth in claim 1, wherein saidwireless communication device receives the signal at a timing of the atleast one reception slot.
 3. The wireless communication device as setforth in claim 1, wherein said wireless communication device transmitsthe beacon signal at a timing of a head of the predetermined frameperiod.
 4. The wireless communication device as set forth in claim 1,wherein said instructions, when executed by the processor, controlstoring timings of reception slots of the another wireless communicationdevice.
 5. The wireless communication device as set forth in claim 1,wherein said instructions, when executed by the processor, controltransmitting a data signal to the another wireless communication deviceat a timing of a reception slot of said another wireless communicationdevice.
 6. A wireless communication device for communicating withanother wireless communication device in an autonomous distributednetwork without a designated control station, said wirelesscommunication device comprising: a processor and a memory includinginstructions which, when executed by the processor, control generating aframe period for setting a predetermined frame period for the wirelesscommunication device, wherein the frame period has a plurality of dataslots serving as data transmission units; setting a scan period, thescan period being longer than said predetermined frame period;performing scan operation for receiving a beacon signal transmitted fromthe another wireless communication device in the scan period set, inwhich the scan operation is to engage in a continuous receivingoperation over a time of said predetermined frame period; analyzing thereceived beacon signal that includes at least one of informationindicating a reception slot or information indicating the predeterminedframe period; and setting at least one reception slot for receiving asignal in said predetermined frame period.
 7. The wireless communicationdevice as set forth in claim 6, wherein said instructions, when executedby the processor, control managing converting a timing of the receivedbeacon signal and a timing of the reception slot into slot positions ofthe wireless communication device.
 8. The wireless communication deviceas set forth in claim 6, wherein said instructions, when executed by theprocessor, control transmitting a data signal at a timing of thereception slot of the another wireless communication apparatus when datais directed to the another wireless communication device.
 9. Thewireless communication device as set forth in claim 6, wherein saidinstructions, when executed by the processor, control timing oftransmission of a beacon signal of the wireless communication device soas not to collide with the beacon signal of the another wirelesscommunication device.
 10. A wireless communication system forcommunication among a plurality of wireless communication devices in anautonomous distributed network without a designated control station,wherein each of the wireless communication devices configuring thenetwork comprises a processor and a memory including instructions which,when executed by the processor, control: generating a frame period forsetting a predetermined frame period for the wireless communicationdevice, wherein the frame period has a plurality of data slots servingas data transmission units; setting at least one reception slot forreceiving a signal in said predetermined frame period; generating abeacon signal that has information about a timing of the reception slotand the predetermined frame period; transmitting the beacon signalnotifying its presence to another wireless communication device locatedin the neighborhood; setting a scan period longer than saidpredetermined frame period; managing a timing of receiving a beaconsignal of the another wireless communication device and the timing ofthe reception slot; performing continuous reception over a time of saidpredetermined frame period and receiving a beacon signal of the anotherwireless communication device located in the neighborhood; and analyzingthe received beacon signal that includes at least one of informationindicating the reception slot or information indicating thepredetermined frame period.
 11. The wireless communication system as setforth in claim 10, wherein the beacon signal is transmitted at a timingof a head of the predetermined frame period.
 12. The wirelesscommunication system as set forth in claim 10, wherein timings by whichthe wireless communication devices transmit beacon signals are arrangedso as not to overlap each other.
 13. A wireless communication method forcommunication among a plurality of wireless communication devices in anautonomous distributed network without a designated control station,wherein each wireless communication device is operable for: generating apredetermined frame period and data slots serving as data transmissionunits for the wireless communication device; setting a scan period, thescan period being longer than said predetermined frame period;performing scan operation to engage in a continuous receiving operationover a time of the predetermined frame period; setting at least onereception slot for receiving a signal in said predetermined frameperiod; generating a beacon signal that includes at least one ofinformation indicating the reception slot or information indicating thepredetermined frame period; and transmitting the beacon signal fornotifying its presence to another wireless communication device locatedin the neighborhood.
 14. A wireless communication method forcommunication among a plurality of wireless communication devices in anautonomous distributed network without a designated control station,wherein each wireless communication device is operable for: generating apredetermined frame period and data slots serving as data transmissionunits for the wireless communication device; setting a scan period, thescan period being longer than said predetermined frame period;performing scan operation to engage in a continuous receiving operationover a time of the predetermined frame period; receiving a beacon signalfrom another wireless communication device located in the neighborhood;analyzing the received beacon signal that includes at least one ofinformation indicating a reception slot or information indicating thepredetermined frame period; setting at least one reception slot forreceiving a signal in a receiving operation in said predetermined frameperiod.